Internet Engineering Task Force Maureen Stillman
INTERNET DRAFT Ram Gopal
Senthil Sengodan
Nokia
Erik Guttman
Sun Microsystems
11 January 2002
expires July 11, 2002
Threats Introduced by Rserpool and Requirements for Security
in response to Threats
<draft-stillman-rserpool-threats-01.txt>
Status of This Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [RFC2026]. Internet-Drafts
are working documents of the Internet Engineering Task Force (IETF),
its areas, and its working groups. Note that other groups may also
distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at
any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at:
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at:
http://www.ietf.org/shadow.html.
Abstract
This Internet draft is an attempt to describe security threats
against the Rserpool protocol. This draft presents requirements for
a security solution to thwart these threats in environments where it
is likely to be deployed. The threats and requirements identified
herein and the document should be considered as work in progress.
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Contents
Status of This Memo 1
Abstract 1
1. Introduction 3
1.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
2. Threats 4
2.1 PE Registration/Deregistration flooding . . . . . . . . . 4
2.2 PE Registration/Deregistration flooding . . . . . . . . . 4
2.3 PE Registration/Deregistration spoofing . . . . . . . . . 4
2.4 PE Registration/Deregistration unauthorized . . . . . . . 5
2.5 Malicious ENRP server joins the group of legitimate ENRP
servers . . . . . . . . . . . . . . . . . 5
2.6 Registration/deregistration with malicious ENRP servers . 5
2.7 Malicious ENRP Name Resolution .. . . . . . . . . . . . . 5
2.8 Malicious node performs a replay attack.. . . . . . . . . 6
2.9 Re-establishing PU-PE security during failover. . . . . . 6
2.10 Integrity . . . . . . . . . . . . . . . . . . . . . . . . 6
2.11 Data Confidentiality . . . . . . . . . . . . . . . . . . 6
2.12 ENRP Server Discovery . . . . . . . . . . . . . . . . . . 7
2.13 Application security . . . . . . . . . . . . . . . . . . 7
3. References 8
4. Acknowledgements 8
5. Author's addresses 8
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1. Introduction
RSERPOOL provides a session layer for robustness and performance. The
session layer function may redirect communication transparently to
upper layers. This alters the direct one-to-one association between
communicating endpoints which typically exists between clients and
services. In particular, secure operation of protocols often relies
on assumptions at different layers regarding the identity of the
communicating party and the continuity of the communication between
endpoints. Further, the operation of RSERPOOL itself has security
implications and risks. The session layer is organized and operates
dynamically which imposes additional concerns for the overall security
of the end-to-end application. This document explores the security
implications of RSERPOOL, both due to its own functions and due to its
being interposed between applications and transport interfaces.
This draft is modeled after [MIPv6 threats] which is a threat analysis
document for Mobile IP V6.
1.1 Definitions
This document uses the following terms:
ENRP Endpoint Name Resolution Protocol:
Within the operational scope of Rserpool, ENRP defines the
procedures and message formats of a distributed fault-tolerant
registry service for storing, bookkeeping, retrieving, and
distributing pool operation and membership information.
ASAP Aggregate Server Access Protocol:
A session layer protocol which uses the Endpoint Name
Resolution Protocol (ENRP) to provide a high
availability name space. ASAP is responsible for the
abstraction of the underlying transport technologies, load
distribution management,fault management, as well as the
presentation to the upper layer (i.e., the ASAP user) a
unified primitive interface.
Operation scope:
The part of the network visible to pool users by a specific
instance of the reliable server pooling protocols.
Pool (or server pool):
A collection of servers providing the same application
functionality.
Pool handle (or pool name):
A logical pointer to a pool. Each server pool will be
identifiable in the operation scope of the system by a unique
pool handle or "name".
ENRP namespace (or namespace):
A cohesive structure of pool names and relations that may be
queried by an internal or external agent.
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Pool element (PE):
A server entity that runs ASAP and has registered to a pool.
Pool user (PU):
A server pool user that runs ASAP. Note, a PU can also be a
PE if it has registered itself to a pool.
ENRP namespace server (or ENRP server):
Entity which runs ENRP and is responsible for managing and
maintaining the namespace within the operation scope.
2. Threats
2.1 PE Registration/Deregistration flooding
Threat: A malicious node could send a stream of false
registrations/deregistrations on behalf of non-existent PEs to ENRP
servers at a very rapid rate and thereby create unnecessary state in an
ENRP server.
Effect: Corrupting the name server database and/or disabling the
Rserpool discovery and naming function.
Requirement: An ENRP server that receives a registration/deregistration
should not create or update state information until it has authenticated
the PE.
2.2 PE Registration/Deregistration flooding
Threat: A malicious node or PE could send a stream of
registrations/deregistrations that are unauthorized to
register/deregister - to ENRP servers at a very rapid rate and thereby
create unnecessary state in an ENRP server.
Effect: Corrupting the name server database and/or disabling the
Rserpool discovery and naming function.
Requirement: An ENRP server that receives a registration/deregistration
should not create or update state information until the authorization of
the registering/de-registering entity is verified.
2.3 PE Registration/Deregistration spoofing
Threat: A malicious node could send false registrations/deregistrations
to ENRP servers concerning a legitimate PE thereby creating false state
information in the ENRP servers.
Effect: Misinformation in the ENRP server concerning a PE would get
propagated to other ENRP servers thereby corrupting the ENRP database.
Requirement: An ENRP server that receives a registration/deregistration
should not create or update state information until it has authenticated
the PE.
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2.4 PE Registration/Deregistration unauthorized
Threat: A PE who is not authorized to join a pool could send
registrations/deregistrations to ENRP servers thereby creating false
state information in the ENRP servers.
Effect: Misinformation in the ENRP server concerning a PE would get
propagated to other ENRP servers thereby corrupting the ENRP database.
Requirement: An ENRP server that receives a registration/deregistration
should not create or update state information until it has authorized
the requesting entity.
2.5 Malicious ENRP server joins the group of legitimate ENRP servers
Threat: Malicious ENRP server joins the group of legitimate ENRP servers
with the intent of propagating inaccurate updates to corrupt the ENRP
database.
Effect: Inconsistent ENRP database state.
Requirement: Mutual authentication of ENRP servers.
2.6 Registration/deregistration with malicious ENRP server
Threat: A PE unknowingly registers/deregisters with malicious ENRP
server.
Effect: Registration might not be properly processed or ignored.
Requirement: PE needs to authenticate the ENRP server.
2.7 Malicious ENRP Name Resolution
Threat: The ASAP protocol receives a name resolution response from an
ENRP server, but the ENRP server is malicious and returns random IP
addresses or an inaccurate list in response to the pool handle.
Effect: PU application communicates with the wrong PE or is unable to
locate the PE since the response is incorrect in saying that a PE with
that name did not exist.
Requirement: ASAP needs to authenticate the ENRP server.
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2.8 Malicious node performs a replay attack
Threat: A malicious node could replay the entire message previously sent
by a legitimate entity. This could create false/unnecessary state in the
ENRP servers when the replay is for registration/de-registration or
update.
Effect: False/extra state is maintained by ENRP servers
Requirement: Care should be taken to prevent replay attacks.
2.9 Re-establishing PU-PE security during failover
Threat: PU fails over from PE A to PE B. In the case that the PU had a
trusted relationship with PE A, then the PU will likely not have the
same relationship established with PE B.
Effect: If there was a trust relationship involving security context
between PU and PE A, the equivalent trust relationship will not exist
between PU and PE B. This will violate security policy.
Requirement: Either notify the application when fail over occurs so the
application can take appropriate action to establish a trusted
relationship with PE B OR reestablish the security context
transparently.
2.10 Integrity
Threats:
a) ENRP response to name resolution is corrupted during transmission
b) ENRP peer messages are corrupted during transmission
c) PE sends update for values and that information is corrupted during
transmission
Effect: ASAP receives corrupt information for pool handle resolution
which the PU believes to be accurate.
Requirement: Integrity mechanism needed.
2.11 Data Confidentiality
Threat: An eavesdropper capable of snooping on fields within messages in
transit, may be able to garner information such as topology/location/IP
addresses etc. that may not be desirable to divulge.
Effect: Information that an administrator does not wish to divulge are
divulged.
Requirement: Provision for Data confidentiality service.
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2.12 ENRP Server Discovery
Threat A thwarting successful discovery: When a PE wishes to register
with an ENRP server, it needs to discover an ENRP server. An attacker
could thwart the successful discovery of ENRP server(s) thereby inducing
the PE to believe that no ENRP server is available. For instance, the
attacker could reduce the returned set of ENRP servers to null or a
small set of inactive ENRP servers.
Threat B: A similar thwarting scenario also applies when an ENRP server
or ASAP on behalf of a PU needs to discover ENRP servers.
Threat C: Spoofing successful discovery: An attacker could spoof the
discovery by claiming to be a legitimate ENRP server. When a PE wishes
to register, it finds the spoofed ENRP server.
Threat D: A similar spoofing scenario also applies when an ENRP server
or ASAP on behalf of a PU needs to discover ENRP servers.
Effect A: A PE that could have been in an application server pool does
not become part of a pool. The PE does not complete discovery operation.
This is a DOS attack.
Effect B: An ENRP server that could have been in an ENRP server pool
does not become part of a pool. A PU is unable to utilize services of
ENRP servers.
Effect C,D: This malicious ENRP would either misrepresent, ignore
or otherwise hide or distort information about the PE to subvert
RSERPOOL operation.
Requirement: Discovery phase needs to be authenticated.
2.13 Security State for Applications
The security context of an application is a subset of the overall
context, and context or state sharing is explicitly out-of-scope for
RSerPool. Because RSerPool does introduce new security vulnerabilities
to existing applications application designers employing RSerPool should
be aware of problems inherent in failing over secured connections.
Security services necessarily retain some state and this state may have
to be moved or re-established. Examples of this state include
authentication or retained ciphertext for ciphers operating in cipher
block chaining (CBC) or cipher feedback (CFB) mode. These problems must
be addressed by the application or by future work on RSerPool.
Requirement: None at this time. Future Rserpool work may address this
issue.
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3. References:
[RFC2026] S. Bradner, "The Internet Standards Process -- Revision 3",
RFC 2026, October 1996.
[MIPv6 threats] draft-team-mobileip-mipv6-sec-reqts-00.txt, July, 2001,
work in progress.
[WHYENC] draft-ietf-saag-whyenc-00.txt, July 2001, work in progress.
[ASAP] R. R. Stewart, Q. Xie: "Aggregate Server Access Protocol
(ASAP)", <draft-ietf-rserpool-asap-00.txt>, work in progress.
[ENRP] Q. Xie, R. R. Stewart "Endpoint Name Resolution Protocol",
draft-ietf-rserpool-enrp-00.txt, work in progress.
4. Acknowledgements
Thanks to the Rserpool security subgroup that provided valuable
comments. Lyndon Ong, Randy Steward, Qiaobing Xie, Michael Tuexen,
Sohrab Modi, Javier Pastor-Balbas, Xingang Guo and Dhooria Manoj.
5. Author's Addresses
Ram Gopal
Nokia Research Center
5 Wayside Road
Burlington, MA 01803
USA
email: ram.gopal@nokia.com
Erik Guttman
Sun Microsystems
Eichhoelzelstr. 7
74915 Waibstadt
Germany
Email: Erik.Guttman@sun.com
Senthil Sengodan
Nokia Research Center
5 Wayside Road
Burlington, MA 01803
USA
email: Senthil.sengodan@nokia.com
Maureen Stillman
Nokia
35 Woodcrest Ave.
Ithaca, NY 14850
USA
email: maureen.stillman@nokia.com
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